This invention is related in general to light beam routing in a computer system, and more particularly, the invention is related to a high speed bus and high speed modular light beam routing for a computer.
Most people familiar with computer-based systems know that the primary mechanism to transfer data from one circuit card to another and for interconnecting the circuit cards is the backplane. Also known as a motherboard, the backplane is typically a printed circuit board with a limited number of sockets into which circuit boards may be inserted. Typically, an interrupt-based bus protocol is used to arbitrate between contending circuit cards requiring access to the bus.
Such backplane-based system bus architectures suffer from several disadvantages. The bandwidth or speed of the system is limited. For example, conventional small PCI (peripheral component interconnect) bus systems run at a maximum aggregate bandwidth of 133 megabytes per second. The number of circuit cards that may be part of the system is also restricted to the number of available sockets on the backplane. The backplane itself also adds weight and size to the system. Many backplanes are also custom designed, thereby adding cost and time to the development cycle.
In order to fully interconnect all circuit cards in the system, a large full access switch is required. Current networking topologies that guarantee data delivery in real time, such as asynchronous transfer mode (ATM) switches, require large switching hubs. Further, in order to achieve large bandwidths, conventional systems use single coax or fiber optic cables to carry the data traffic. Each link also requires a dedicated network adaptor card.
A unique system application is for those systems that require a separation of secured or encrypted and unsecured or decrypted data. Conventional systems use complex networks of discrete filters to isolate the secured or encrypted data from the unsecured data. These discrete filters take up extra space and require elaborate tests to verify the isolation of the secured data. Further, the speed of the backplane is adversely impacted.
In accordance with the present invention there is provided a bus module providing mechanical, electrical, optical, and power interface for individual circuit cards and for network adaptability. Each bus module provides low latency interconnectivity between modules for data packet transfer, such as 32-bit word read and write. Interconnectability of the bus module provides near unrestricted expansion of a computer backplane.
Each bus module includes an optical interfacexe2x80x94left and optical interfacexe2x80x94right. Each interface comprises a two-dimensional N by N, for example 16xc3x9716, bi-directional array of VCSEL (vertical cavity surface emitting laser)/photodetector elements. Each bi-directional VCSEL/photodetector element functions to provide high speed data communication through interconnected adjacent bus modules from one module in the interconnection to any other module by means of a pre-programmed transfer path through VCSEL/photodetector elements arranged in a row by column matrix. This provides the advantage of a high-speed data transfer without the need for a header for each data packet. The interconnection of one circuit card to other circuit cards through the interconnected bus modules is along a fixed path known to both the transmitting circuit card and the receiving circuit card.
In accordance with the present invention VCSEL/photodetector element arrays pass data to each other over free space. Bus alignment is an important aspect of this interconnect technology that allows programmed interconnect schemes by establishing dedicated channels from bus module xe2x80x9cmxe2x80x9d to bus module xe2x80x9cnxe2x80x9d, where xe2x80x9cmxe2x80x9d and xe2x80x9cnxe2x80x9d are within the range of 2 to N. By establishing such dedicated data links switching data transfer is simplified. The number of modules xe2x80x9cCxe2x80x9d that can be interconnected is valid for all positive values of xe2x80x9cCxe2x80x9d and xe2x80x9cmxe2x80x9d satisfying the equation C(Cxe2x88x921) less than 2 m.
In accordance with the present invention, there is provided an optical data transfer network comprising at least one network backplane bus module having a global electrical bus, a local electrical bus, and an optical bus. A plurality of bi-directional optical/electrical converters coupled to the optical bus converts optical signals to electrical signals and vice versa. An optical link interface coupled between the local electrical bus and the bi-directional optical electrical converters routes data between the local electrical bus and the optical bus. A controller coupled to an optical link interface provides signals for controlling data routing between the local electrical bus, the global electrical bus and the optical bus.